Electronic device and protection circuit and protection method

Abstract

A protection method is executed by an electronic device that is powered by a supply voltage of a power source. The protection method includes steps of: storing a power-off threshold voltage; detecting the supply voltage of the power source to generate a detecting voltage; determining whether the detecting voltage is equal to the power-off threshold voltage; beginning to count for a predetermined period of time when the detecting voltage is equal to the power-off threshold voltage and acquiring the detecting voltage during the predetermined period of time; determining whether each acquired detecting voltage is smaller than the power-off threshold voltage; and generating a first control signal when one of the acquired detecting voltages is larger than or is equal to the power-off threshold voltage; wherein the first control signal controls a processor of the electronic device to stop performing a power-off procedure.

What is claimed is: 
     
         1 . A protection circuit causing an electronic device that is powered by a supply voltage of a power source to be protected, the electronic device comprising a processor that is capable of performing a power-off procedure to cause the electronic device to be powered off, the protection circuit comprising:
 a storage unit storing a power-off threshold voltage;   a detecting unit detecting the supply voltage of the power source to generate a detecting voltage; and   a comparator determining whether the detecting voltage is equal to the power-off threshold voltage, beginning to count for a predetermined period of time when the detecting voltage is equal to the power-off threshold voltage, and acquiring the detecting voltage from the detecting unit during the predetermined period of time;   wherein the comparator further determines whether each acquired detecting voltage is smaller than the power-off threshold voltage, and generates a first control signal when one of the acquired detecting voltages is larger than or is equal to the power-off threshold voltage; the first control signal controls the processor to stop performing the power-off procedure.   
     
     
         2 . The protection circuit of  claim 1 , wherein the comparator further generates a second control signal when all acquired detecting voltages are smaller than the power-off threshold voltage, the second control signal controls the processor to perform the power-off procedure. 
     
     
         3 . The protection circuit of  claim 1 , wherein the electronic device further comprises a power management unit and a load, the power management unit is capable of allowing the supply voltage of the power source to be transmitted to the load, the storage unit further stores a predetermined voltage drop in the supply voltage due to power failure of the power source and an over-discharge protection voltage; the comparator further determines whether the detecting voltage is smaller than the over-discharge protection voltage and generates a third control signal when the detecting voltage is smaller than the over-discharge protection voltage; the third control signal enables the processor to control the power management unit to prevent the supply voltage of the power source from reaching the load, the power-off threshold voltage is equal to a sum of the over-discharge protection voltage and the predetermined voltage drop. 
     
     
         4 . The protection circuit of  claim 3 , wherein the comparator further generates a fourth control signal when the detecting voltage is larger than or is equal to the over-discharge protection voltage, the fourth control signal enables the processor to control the power management unit to allow the supply voltage of the power source to be transmitted to the load. 
     
     
         5 . The protection circuit of  claim 2 , wherein the storage unit storing a predetermined duration of time of power failure of the power source, and the predetermined period of time is larger than the predetermined duration of time. 
     
     
         6 . The protection circuit of  claim 5 , wherein the predetermined period of time is equal to a sum of the predetermined duration of time and one second. 
     
     
         7 . The protection circuit of  claim 5 , wherein during the predetermined period of time, the comparator acquires the detecting voltage from the detecting unit at a predetermined interval, the predetermined interval is equal to the predetermined duration of time divided by 20. 
     
     
         8 . The protection circuit of  claim 3 , wherein there are a plurality of voltage drops in the supply voltage of the power source respectively due to a plurality of power failure of the power source, and the predetermined voltage drop is equal to one of the plurality of voltage drops which has a maximum value. 
     
     
         9 . The protection circuit of  claim 5 , wherein there are a plurality of durations of power failure of the power source, and the predetermined duration of time is equal to one of the plurality of durations which has a maximum value. 
     
     
         10 . A electronic device powered by a supply voltage of a power source, the electronic device comprising:
 a processor capable of performing a power-off procedure to cause the electronic device to be powered off; and   a protection circuit comprising:   a storage unit storing a power-off threshold voltage;   a detecting unit detecting the supply voltage of the power source to generate a detecting voltage; and   a comparator determining whether the detecting voltage is equal to the power-off threshold voltage, beginning to count for a predetermined period of time when the detecting voltage is equal to the power-off threshold voltage, and acquiring the detecting voltage from the detecting unit during the predetermined period of time;   wherein the comparator further determines whether each acquired detecting voltage is smaller than the power-off threshold voltage, and generates a first control signal when one of the acquired detecting voltages is larger than or is equal to the power-off threshold voltage; the processor stops performing the power-off procedure in response to the first control signal.   
     
     
         11 . The electronic device of  claim 10 , wherein the comparator further generates a second control signal when all acquired detecting voltages are smaller than the power-off threshold voltage, the processor performs the power-off procedure in response to the second control signal. 
     
     
         12 . The electronic device of  claim 10 , wherein the electronic device further comprises a power management unit and a load, the power management unit is capable of allowing the supply voltage of the power source to be transmitted to the load, the storage unit further stores a predetermined voltage drop in the supply voltage due to power failure of the power source and an over-discharge protection voltage; the comparator further determines whether the detecting voltage is smaller than the over-discharge protection voltage and generates a third control signal when the detecting voltage is smaller than the over-discharge protection voltage; the third control signal enables the processor to control the power management unit to prevent the supply voltage of the power source from reaching the load, the power-off threshold voltage is equal to a sum of the over-discharge protection voltage and the predetermined voltage drop. 
     
     
         13 . The electronic device of  claim 12 , wherein the comparator further generates a fourth control signal when the detecting voltage is larger than or is equal to the over-discharge protection voltage, the fourth control signal enables the processor to control the power management unit to allow the supply voltage of the power source to be transmitted to the load. 
     
     
         14 . The electronic device of  claim 11 , wherein the storage unit storing a predetermined duration of time of power failure of the power source, and the predetermined period of time is larger than the predetermined duration of time. 
     
     
         15 . The electronic device of  claim 12 , wherein there are a plurality of voltage drops in the supply voltage of the power source respectively due to a plurality of power failure of the power source, and the predetermined voltage drop is equal to one of the plurality of voltage drops which has a maximum value. 
     
     
         16 . The electronic device of  claim 14 , wherein there are a plurality of durations of power failure of the power source, and the predetermined duration of time is equal to one of the plurality of durations which has a maximum value. 
     
     
         17 . A protection method executed by an electronic device that is powered by a supply voltage of a power source, the electronic device comprising a processor that is capable of performing a power-off procedure to cause the electronic device to be powered off, the protection method comprising steps of:
 storing a power-off threshold voltage;   detecting the supply voltage of the power source to generate a detecting voltage;   determining whether the detecting voltage is equal to the power-off threshold voltage;   beginning to count for a predetermined period of time when the detecting voltage is equal to the power-off threshold voltage and acquiring the detecting voltage during the predetermined period of time;   determining whether each acquired detecting voltage is smaller than the power-off threshold voltage; and   generating a first control signal when one of the acquired detecting voltages is larger than or is equal to the power-off threshold voltage; wherein the first control signal controls the processor to stop performing the power-off procedure.   
     
     
         18 . The protection method of  claim 17 , further comprising the step of:
 generating a second control signal when each acquired detecting voltage is smaller than the power-off threshold voltage, the second control signal controls the processor to perform the power-off procedure.   
     
     
         19 . The protection method of  claim 17 , wherein the electronic device further comprises a power management unit and a load, the power management unit is capable of allowing the supply voltage of the power source to be transmitted to the load, the protection method further comprises the steps of:
 storing a predetermined voltage drop in the supply voltage due to power failure of the power source and an over-discharge protection voltage;   determining whether the detecting voltage is smaller than the over-discharge protection voltage; and   generating a third control signal when the detecting voltage is smaller than the over-discharge protection voltage;   wherein the third control signal enables the processor to control the power management unit to prevent the supply voltage of the power source from reaching the load, the power-off threshold voltage is equal to a sum of the over-discharge protection voltage and the predetermined voltage drop.   
     
     
         20 . The protection method of  claim 19 , wherein there are a plurality of voltage drops in the supply voltage of the power source respectively due to a plurality of power failure of the power source, and the predetermined voltage drop is equal to one of the plurality of voltage drops which has a maximum value.